1. Field of the Invention
The present invention relates generally to a weak-magnetic field sensor using printed circuit board technology and method of manufacturing the same, and more particularly to a weak-magnetic field sensor using printed circuit board technology and method of manufacturing the same, in which a rectangular ring-shaped magnetic core is wound by exciting circuit patterns and detecting circuit patterns, and weak-magnetic field sensors are implemented in x-axis and y-axis directions, respectively, to precisely calculate azimuth, thereby sensing a weak-magnetic field having a strength similar to that of earth's magnetic field.
2. Description of the Prior Art
Recently, as various kinds of information services are expanded according to the spread of mobile phones and mobile terminals, location information services have become basic functions, but more detailed and convenient services are required in the future. Additionally, a sensor capable of sensing a current location is needed to obtain desired location information.
For a means for providing the location information, a weak-magnetic field sensor for sensing the earth's magnetic field and detecting a location, that is, a magnetic sensor for sensing the earth's weak magnetic field using magnetic materials and coils, has been used for highly sensitive magnetic sensors.
The conventional weak-field magnetic sensor is formed by winding a conductive coil by hand around a relatively large bar core or ring core formed of a magnetic ribbon. Additionally, an electronic circuit is needed to obtain a magnetic field proportional to a measurement magnetic field. For example, a flux-gate magnetic sensor is used as general parts of the conventional weak-magnetic field sensor. The flux-gate magnetic sensor uses a core formed of a high permeability magnetic material, and recognizes a direction using voltage difference generated from a primary coil winding the magnetic core, thus sensing a weak magnetic field.
The conventional flux-gate magnetic sensor is formed by winding a copper wire made of copper around a circular-shaped magnetic core in a regular direction. In detail, in the flux-gate magnetic sensor, a driving coil (primary coil) is formed by winding a copper wire made of copper around the magnetic core in a regular direction with regular intervals and stress to generate a magnetic field in the magnetic core. Thereafter, a pick-up coil (secondary coil) is formed to sense the magnetic field generated in the magnetic core by the driving coil, and in this case, the pick-up coil is also formed by winding a copper wire around the magnetic core with regular intervals and stress.
As described above, the flux-gate magnetic sensor formed by winding the copper wires includes the driving coil and the pick-up coil for detecting the magnetic field generated in the magnetic core by the driving coil. The driving and pick-up coils are wound around the magnetic core using wire coil technology previously widely known. In this case, the secondary coil should be wound to be perpendicular to x-axis and y-axis directions because it should precisely analyze the sensitivity of the magnetic field.
In the conventional flux-gate magnetic sensor, the coils should be accurately wound around the core. It is difficult to maintain such location accuracy due to the wires having a diameter of several tens of micrometers. Accordingly, since the wires are influenced by temperature, light and surface material, the location accuracy of the coils is deteriorated.
Additionally, the flux-gate magnetic sensor is problematic in that the coils are directly wound around the magnetic core, so that the coils are frequently cut. Further, the size of the sensor is increased, so the sensor does not correspond to a trend toward miniaturization and slimness of electronic devices and, therefore, its power consumption is increased.
To solve the problems of the conventional flux-gate magnetic sensor, a weak-magnetic field sensor is disclosed in U.S. Pat. Nos. 5,936,403 and 6,270,686. In these Patents, an amorphous core is formed by stacking two amorphous boards, each having a circular conductor pattern, on opposite sides of an epoxy base board, which has a particular pattern etched thereon and the capacity for vertical conductivity, and epoxy bases, which have a coil X and a coil Y, respectively, are stacked on the top and bottom surfaces of the amorphous core.
However, in the U.S. Pat. No. 5,936,403, since the amorphous core is formed by stacking the two amorphous boards each having the circular pattern, on opposite sides of the epoxy base board to correspond to the circular patterns, the manufacturing process of the weak-magnetic field sensor is complicated and the manufacturing cost thereof is increased due to many layers of the sensor.